JPH08234212A - Liquid crystal display element - Google Patents

Abstract

PURPOSE: To provide a liquid crystal display element capable of making the pass quantity of light at every pixel uniform and preventing the light from being incident on switching elements. CONSTITUTION: Since columnar spacers 24 are formed above TFTs 22 on a display driving panel 11 side out of a resin having light shieldability to eliminate the need for forming spacers on pixel electrodes 17, the quantity of the light passing the respective pixel electrodes is made uniform. Since the spacers 24 are formable at every pixel, the intra-surface uniformity of the gap between both panels is improved when a display driving panel 11 and a common electrode panel 12 are stuck to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device.

[0002]

2. Description of the Related Art As a conventional liquid crystal display element, one shown in FIG. 8 is known. As shown in the figure, the structure of this liquid crystal display element is such that a plurality of pixel electrodes 2 and thin film transistors (hereinafter referred to as TFTs) 3 as switching elements connected to the pixel electrodes 2 are provided on the lower glass substrate 1 side. The common electrode 5 and the black matrix 6 are provided on the upper glass substrate 4 side. Black matrix 6
Are arranged at positions facing the TFT 3 and the like. Alignment films 7 and 8 are formed on the inner surfaces of the glass substrates 1 and 4 facing each other. A large number of spacers (gap members) 9 formed by, for example, processing a resin into a spherical shape are interposed between the glass substrates 1 and 4 in order to maintain a predetermined space between the glass substrates 1 and 4. The spacers 9 are arranged by being sprayed on the alignment film of one of the glass substrates before the lower glass substrate 1 and the upper glass substrate 4 are bonded together. The liquid crystal 10 is filled in the gap formed between the glass substrates 1 and 4 by such a spacer 9 to form a liquid crystal display element.

[0003]

However, in such a conventional liquid crystal display element, since the method of spreading the spacers 9 on the alignment film of one of the glass substrates is adopted, the spacers 9 are formed on the pixel electrodes 2. Since the spacer 9 is naturally formed on the alignment film 7 of the above, the spacer 9 always transmits the light incident between the substrates, or disturbs the alignment of the liquid crystal molecules, and the pixel 9 There is a problem that it becomes difficult to adjust the amount of light passing through the electrode 2 and color development, and the display quality is degraded. In addition, since the spacer 9 is made of resin, static electricity is easily charged, and therefore particles are likely to collect each other, and it is difficult to uniformly distribute the spacer 9 by spraying. FIG. 9 is an explanatory plan view showing a distribution state of the spacers 9 scattered on the lower glass substrate 1. As can be seen from the figure, depending on the pixel electrode 2, there is no spacer 9 at all.
In some cases, the distribution of the spacers 9 is unbalanced, and there are some in which the spacers 9 are not scattered and many in which the spacers 9 are gathered. Therefore, there is a problem that the amount of light passing through each pixel is different. Further, as shown in FIG. 8, even though the black matrix 6 is formed on the upper glass substrate 4 side, the light incident from an oblique direction is T
Since the electron-hole pairs are excited by being incident on the semiconductor layer of FT3, there is a problem that the electrical characteristics of the TFT3 as a switching element are changed and the display quality is deteriorated.

An object of the present invention is to provide a liquid crystal display element which does not disturb the alignment of liquid crystal molecules on a pixel and can prevent light from entering a switching element.

[0005]

In view of the above, according to the invention of claim 1, liquid crystal is sealed between a pair of substrates each having a display electrode provided in a display area of a surface facing each other, and at the same time, a liquid crystal is enclosed between the pair of substrates. In a liquid crystal display element in which display electrodes on one of the substrates are arranged in a matrix and switching elements are connected to the display electrodes, a light-shielding spacer is provided at least on the switching elements. I am trying. The invention according to claim 2 is
The switching element is a thin film transistor, a gate electrode of the thin film transistor is connected to a gate line connected to a scan driving circuit, a drain electrode of the thin film transistor is connected to a drain line connected to a signal driving circuit, the spacer is Patterning is performed on the thin film transistor and at least one of the gate line and the drain line. The invention according to claim 3 is characterized in that the spacer is formed by coating a surface of a patterned transparent resin with a light-shielding material film. The invention according to claim 4 is characterized in that the liquid crystal is a polymer-dispersed liquid crystal.

[0006]

According to the present invention, the display electrodes on one of the substrates are arranged in a matrix, and the switching electrodes are connected to the display electrodes, respectively, and the spacers are provided at least on the switching elements. Therefore, a spacer is not provided on the display electrode of this one substrate, and the amount of light passing through each pixel is uniform because the pixel is always filled with liquid crystal, and the alignment state of the liquid crystal of the pixel due to the spacer is uniform. Since there is almost no turbulence, the amount of light passing is the same. Therefore, it has an effect of improving the display quality. Further, since the spacer has a light shielding property, it has a function of preventing light from entering the switching element. Therefore, when the switching element is a thin film transistor, it has an effect of preventing light from entering the semiconductor layer and changing electrical characteristics. Further, in the invention according to claim 2, since the spacer is patterned on the thin film transistor, the gate line and the drain line, it has an effect of further improving the in-plane uniformity of the gap between the pair of substrates. . Further, since it is not necessary to provide the black matrix on the other substrate side, the flatness of the substrate can be improved. Further, in the invention according to claim 3, since the spacer can be formed by patterning the transparent resin which can be easily aligned in the photolithography process and then coating the light-shielding material film on the surface of the transparent resin.
The spacer can be reliably formed on the switching element or the like. Further, in the invention according to claim 4, even if the spacer is formed on the thin film transistor, the gate line and the drain line so as to form a lattice shape, the liquid crystal to be enclosed is a polymer dispersed liquid crystal,
This liquid crystal can be embedded in the recess formed by the spacer before the two substrates are bonded together.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the liquid crystal display device according to the present invention will be described below with reference to the respective embodiments shown in the drawings. (Embodiment 1) FIG. 1 is a sectional view showing a main part of an active matrix type liquid crystal display device to which the embodiment 1 of the present invention is applied, and FIG. 2 is an active matrix type liquid crystal display device to which the embodiment 1 is applied. FIG. 3 is a perspective view of a main part of one substrate side.
In this liquid crystal display element, a common electrode panel 12 serving as the other substrate is bonded onto a display drive panel (TFT panel) 11 serving as one of the substrates facing each other via a sealing material (not shown), and a space between them. The liquid crystal 13 is enclosed in the structure.

The display drive panel 11 has a lower transparent substrate 14 made of glass or the like. On the upper surface of the lower transparent substrate 14, there are provided a gate electrode 15A made of, for example, aluminum at a predetermined position, and a gate line 15 (see FIG. 2) collectively formed so as to be connected to the gate electrode 15A. Has been formed. In addition, this gate line 1
Reference numeral 5 is set so as to be laid along one side of a pixel electrode 17, which will be described later, and is connected to a scan drive circuit (not shown). The gate insulating film 1 made of, for example, silicon oxide or silicon nitride is formed on the upper surface of the gate electrode 15A, the gate line 15 and the exposed lower transparent substrate 14.
6 is deposited on the entire surface.

Further, a pixel electrode 17 made of ITO is formed in one pixel formation region on the gate insulating film 16, and a rectangular cutout 17A is formed at one corner as shown in FIG. It is formed in a shape. The gate electrode 15A is designed to be located below the cutout 17A. Notch 17A of this pixel electrode 17
The gate electrode 15A on the gate insulating film 16 in
A semiconductor layer 18 made of intrinsic amorphous silicon or the like is patterned as an active layer of a TFT (thin film transistor; switching element) at a position opposed to. A blocking layer 19 made of silicon nitride or the like is formed in the center of the semiconductor layer 18 so as to cross the semiconductor layer 18 along the gate width direction, and both sides of the blocking layer 19 on the semiconductor layer 18 are sandwiched. A source electrode 20 and a drain electrode 21A are formed on each of them via a high impurity concentration semiconductor layer. As shown in FIGS. 1 and 2, the end portion of the source electrode 20 has a cutout portion 17 of the pixel electrode 17.
A pattern is formed so as to overlap the edge portion of A, and they are electrically connected to each other. On the other hand, the drain electrode 21
A is formed together with the drain line 21 which is laid so that the side of the pixel electrode 17 is orthogonal to the gate line 15. The drain line 21 is connected to a signal drive circuit (not shown). There is. 22 in the figure
Is the gate electrode 15A, the gate insulating film 16, the semiconductor layer 1
8, a TFT including a source electrode 20, a drain electrode 21A and the like is shown.

The lower transparent substrate 14 on which the pixel electrodes 17 and the TFTs 22 as switching elements are thus formed.
As shown in FIG. 1, a lower alignment film 23 is formed on the entire upper surface of the. Then, the TFT on the lower alignment film 23
As shown in FIGS. 1 and 2, a spacer 24, which is made of, for example, a resin having a light-shielding property and is formed into a columnar shape having a rectangular cross section, is provided at a position facing 22. In FIG. 2, the lower alignment film 23 is omitted. The spacer 24 is formed by applying resin on the entire surface of the lower alignment film 23,
It can be formed using a lithographic technique and a wet etching technique. Such a spacer 24
2 are formed one by one in each pixel as shown in FIG. 2, and thus improve the in-plane uniformity of the spacing between the display drive panel 11 and the common electrode panel when the common electrode panel is attached later. be able to. In particular, for example the spacer 24
After adjusting the viscosity of the resin constituting the above, the resin is spin-coated on the display drive panel 11 so that the resin surface becomes flat.
Even if there are steps such as irregularities on the surface of the
The height of 4 can be made uniform.

Thereafter, as shown in FIG. 1, the common electrode panel 1 is mounted on the surface drive panel 11 via a sealing material (not shown).
When the two are bonded together, the upper alignment film 25 provided on the common electrode panel 12 side abuts on the upper end of the spacer 24, so that the distance between the panels 11 and 12 can be kept uniform.
The common electrode panel 12 includes the common electrode 2 made of ITO on the entire display area on the lower surface of the upper transparent substrate 26 made of glass or the like.
7 is formed, and the above-described upper alignment film 25 is formed on the entire surface on the common electrode 27 and the exposed lower surface of the upper transparent substrate 26. In the present embodiment, since the spacer 24 has a light-shielding property, it is not necessary to provide a black matrix at the position facing the TFT 22 on the common electrode panel 12 side, and there is an advantage that the manufacturing process of the common electrode panel 12 can be simplified. .
In addition, since it is only necessary to form the spacer 24 only in the portion where the TFT 22 is present, it is possible to realize the manufacture of a liquid crystal display element having a good display quality without reducing the passing amount of the light incident on the pixel electrode 17. You can Since the spacer 24 has a columnar shape, the spacer 24 does not hinder the liquid crystal 13 from entering the gap between the panels in the step of filling the liquid crystal 13.

(Embodiment 2) FIG. 3 is a sectional view showing a main part of an active matrix type liquid crystal display device to which Embodiment 2 of the present invention is applied. In this embodiment, the spacer 24 provided above the TFT 22 in the first embodiment is used as the transparent portion 2.
4A and the light shielding portion 24B, and other configurations are the same as those in the first embodiment. To form the spacers 24, first, a transparent resin is coated on the lower alignment film 23, a photoresist is patterned on the transparent resin by a lithography technique, and wet etching is performed using the photoresist as a mask. Next, the light-shielding portion 24B may be formed by adsorbing a material having a light-shielding property such as a pigment on the surface of the patterned transparent portion 24A. With such a configuration of the spacer 24, the positioning means such as the alignment mark (alignment mark) formed on the display drive panel 11 side can be well recognized when patterning the transparent portion 24A, and the body of the spacer 24 can be recognized. It is possible to dispose the transparent portion 24A forming the above at a certain position.

(Embodiment 3) FIG. 4 is a drawing showing a plane on the display drive panel 11 side of an active matrix type liquid crystal display element to which Embodiment 3 of the present invention is applied. In this embodiment, the spacer 24 is formed above the TFT 22 and the portion where the gate line 15 and the drain line 21 in the vicinity cross each other (on the lower alignment film). Similar to Example 1. Also in this embodiment,
Since there is no spacer in the pixel electrode 17, the pixel electrode 1
Since the pixel electrodes 17 are filled with the liquid crystal without disturbing the alignment of the liquid crystal molecules on 7, the liquid crystal display element with good display quality can be manufactured. Further, also in the present embodiment, since the spacer 24 is columnar, the spacer 24 hardly interferes with the entry of the liquid crystal 13 into the gap between the panels in the step of filling the liquid crystal 13.

(Embodiment 4) FIG. 5 is a drawing showing a plane on the display drive panel 11 side of an active matrix type liquid crystal display device to which Embodiment 4 of the present invention is applied, and FIG.
(A) and (B) are respectively AA sectional view and BB of FIG.
It is sectional drawing. In this embodiment, the spacer 24 is formed on the lower alignment film 23 in the display drive panel 11 so as to cover the gate line 15, the drain line 21 and the TFT 22 (position above these lines and the TFT 22).
Are formed in a grid pattern. As shown in FIGS. 6A and 6B, the spacer 24 </ b> C at the intersection of the gate line 15 and the drain line 21 has the display drive panel 11.
Has a height that defines a gap between the common electrode panel 12 and
The height of the spacer 24D between the spacers 24C is set low so as to allow the inflow of liquid crystal. To form such a spacer 24, a resist mask is formed on the spacer 24C portion and wet etching is performed, and the wet etching is stopped when the height of the spacer 24D portion reaches a predetermined height. Can be formed. Also in the present embodiment, the spacer 24 does not interfere with the inflow of the liquid crystal, and a smooth liquid crystal filling process can be performed. Moreover, since the spacers 24C and 24D are integrally formed, the spacers 24C and 24D have high strength and do not peel off from the lower alignment film. Also, the spacer 2
4 is a gate line 15, a drain line 21 and a TF
Since the structure covers T22, the diffused reflection of the gate line 15, the drain line 21, and the TFT 22 is blocked.
There is no need to form a black matrix on the common electrode panel side. Although the spacers are formed on the gate line and the drain line in the above embodiment, only one of the lines may be formed.

(Embodiment 5) FIG. 7 shows a plane of a display drive panel of an active matrix type liquid crystal display device to which Embodiment 5 of the present invention is applied. In this embodiment, the region where the spacer 24 is formed is exactly the same as that of the above-described fourth embodiment, and the gate line 15, the drain line 21 and the T line are formed.
It is formed so as to cover the FT 22. And the spacer 24
The height of was set to be the same in all parts. For this reason,
The pixel electrode 17 surrounded by the spacer 24 is located at the bottom of the recess. In such a structure, it is difficult to fill a normal liquid crystal, and therefore a polymer-dispersed liquid crystal can be used by embedding it in the recess. The polymer-dispersed liquid crystal may be a liquid crystal that has already been encapsulated, or may have a structure in which the liquid crystal is dispersed in a reticulated polymer by filling the recess with a solution in which the polymer material and the liquid crystal are compatible, and then polymerizing the polymer material. Good. Therefore, there is no need to form a black matrix on the common electrode panel side, and there is an advantage that the manufacturing process can be simplified. The rest of the configuration of this embodiment is similar to that of the first embodiment.

The first to fifth embodiments have been described above.
The present invention is not limited to these, and various design changes associated with the gist of the configuration are possible. For example, although the TFT 22 is applied as the switching element in each of the above embodiments, the present invention is not limited to this, and an MIM element may be applied.
Further, in each of the above-described embodiments, the spacer 24 is made of resin, but it may be made of an inorganic material such as silicon oxide or silicon nitride.

As is apparent from the above description, according to the present invention, since there is no spacer (gap material) on the pixel electrode, the display quality is improved. Further, since the switching element (for example, a thin film transistor) is covered with a light-shielding spacer, light from an oblique direction does not enter the switching element, and the electrical characteristics of the switching element are not affected by light. It has the effect of favorably driving the liquid crystal. Furthermore, since the height of the spacer can be determined in advance even if there are irregularities on the inner surface of the substrate on which the switching elements are formed facing each other, there is an effect of improving the in-plane uniformity of the gap size between both substrates.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing a first embodiment of the present invention.

FIG. 2 is a perspective view of the display drive panel according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view of essential parts showing Embodiment 2 of the present invention.

FIG. 4 is a plan view of a display drive panel according to a third embodiment of the present invention.

FIG. 5 is a plan view of a display drive panel according to a fourth embodiment of the present invention.

6A is a sectional view taken along line AA of FIG. 5, and FIG. 6B is a sectional view taken along line BB of FIG.

FIG. 7 is a plan view of a display drive panel according to a fifth embodiment of the present invention.

FIG. 8 is a sectional view of a main part of a conventional liquid crystal display element.

FIG. 9 is an explanatory plan view of a conventional liquid crystal display element.

[Explanation of symbols]

 11 display drive panel 12 common electrode panel 13 liquid crystal 14 lower transparent substrate 15 gate line 17 pixel electrode 21 drain line 22 TFT 23 lower alignment film 24 spacer 24A transparent part 24B light shielding part 25 upper alignment film 26 upper transparent substrate 27 common electrode

Claims (4)

[Claims] 1. A liquid crystal is sealed between a pair of substrates, each of which has a display electrode provided in a display area of a surface facing each other, and display electrodes of one of the two substrates are arranged in a matrix. A liquid crystal display element in which a switching element is connected to each of the display electrodes, wherein a spacer having a light shielding property is provided at least on the switching element. 2. The switching element comprises a thin film transistor, a gate electrode of the thin film transistor is connected to a gate line connected to a scan driving circuit, and a drain electrode of the thin film transistor is connected to a drain line connected to a signal driving circuit. 2. The liquid crystal display device according to claim 1, wherein the spacer is patterned on the thin film transistor and at least one of the gate line and the drain line. 3. The liquid crystal display element according to claim 1, wherein the spacer is formed by coating a surface of a patterned transparent resin with a light-shielding material film. 4. The liquid crystal display device according to claim 1, wherein the liquid crystal is a polymer dispersed liquid crystal.